Question

what is combustion reaction? give the reaction for when methane is burnt in limited air

Answer 1

The reaction in which a large amount of heat is evolved is called combustion reaction.

If very limited air is supplied, then Methane gives carbon black.

The reaction is as follows:-

       CH4    +        O2     =    C    +     2H2O

       where,

                   O2 is limited air and C is carbon black

Answer 2

Rapid chemical combination of a substance with oxygen, involving the production of heat and light is called Combustion.
The reaction is as follows:
CH₄ + 2O₂ -----------> CO₂ + 2H₂O.